1. Field of the Invention
This invention relates generally to structural fastener members and particularly to a new and novel fastener member that may be used with a penetrable plate or sheet to facilitate construction at a job site and to provide a much improved composite structural unit when erected in a building or the like.
2. Description of the Related Art
The use of fasteners in the construction of composite structural members such as flat plywood stressed-skin panels is well known in the art. These previously known fasteners typically comprised structural glues to rigidly secure the plywood skins to spaced lumber web members. With this type of construction, both materials (plywood and lumber) were designed to act compositely or in unison due to the glue bond between them.
Since stressed-skin panels were usually relatively shallow, any shear deformation between the skins and the webs contributed materially to vertical deflection. For maximum stiffness, therefore, it was the conventional practice with many of the previously known panel fabricators to glue the plywood skins to the framing members using clamping or other positive mechanical means to ensure good glue bond. In place of mechanical pressure methods, nailing was often used with the nails spaced approximately three to four inches apart along all glued contact areas. Gluing was disadvantageous, however, in that it required special shop-like conditions yto cure properly, and it required additional materials, i.e., the nails, and it was more time consuming to fabricate, and therefore, more expensive in labor costs.
Metallic fasteners with protruding prongs or teeth have also been tried and used with varying degrees of success for joining and fastening various members together. For example in the U.S. Pat. No. 1,140,687, issued May 25, 1915 to V. E. Lane there is taught a fastening device for holding insulation with the device consisting of a series of pointed metallic teeth which penetrate the insulation and which are then bent over at their ends. An insulation block holder for joining insulation blocks to a refrigerator wall using pointed metallic teeth is taught in the U.S. Pat. No. 3,967,524, issued to K. T. Snow et al on July 6, 1976.
A modified type of metallic tooth or prong fastener for use in reinforcing asbestos and other fibrous insulations is taught in the U.S. Pat. No. 2,359,205, issued Sept. 26, 1944 to A. M. Cowan while the same general type fastener has been used to reinforce timber structures as taught in the U.S. Pat. No. 4,586,550, issued to S. Kitipornchai on May 6, 1986.
A multi-pointed metallic fastener for joining wooden joints in building construction is taught in the U.S. Pat. No. 3,416,821, issued to E. L. Benno on Dec. 17, 1968. A multi-pointed plate member has also been utilized to form a structural member as taught in the U.S. Pat. No. 1,075,845, issued to J. H. Mills on Oct. 14, 1913. This device uses inwardly turned pointed tabs on the plate to fasten to internally positioned wooden members to form the structural shape desired.
The use of pointed metallic tabs to form a structural member was also tried in the later invention of H. Hess in 1954 as taught in the German patent No. 1,004,790. This invention uses an elongated metal sheet web which has pointed teeth formed along the lateral edges of the web with the teeth being embedded into oppositely spaced penetrable members and with the entire structure being held together by long bolts.
The Hess basic concept of using pointed teeth on a structural web evolved in later applications as taught in the two U.S. patents issued to J. C. Falkenberg in 1975 and 1976. The first Falkenberg U.S. Pat. No. 3,872,641, issued on Mar. 25, 1975, uses a corrugated web with sharp reverse bend teeth for use in joining oppositely spaced penetrable panels. The second Falkenberg U.S. Pat. No. 3,938,289 issued on Feb. 17, 1976 and was a variation of the earlier design with pointed teeth positioned on the structural web member.
In the U.S. Pat. No. 3,938,289 to Falkenberg it has been proposed that a metal web element containing trapezoidal corrugations with teeth extending outward therefrom serve as a force transferring member in a load bearing beam or panel structure. Such a web, as described, has little practical value in that the corrugations in the web would straighten out longitudinally when subjected to the normal tension stresses that develop in the web when a beam or panel is loaded, thus resulting in excessive deflection. This structure would also require three separate elements to function--a metal web and two opposed plates.
While the later developed web structures with attached pointed teeth, such as the two before mentioned Falkenberg patents may have overcome the disadvantages of gluing and nailing used in earlier structures; there have been introduced in the later structures, other design problems inherent in the particular structure. For example, the U.S. Pat. No. 3,905,171 issued on Sept. 16, 1975 to D. A. Cargill et al uses a metallic web with teeth formed at one or both edges thereof to join opposed penetrable plate members such as plywood. As shown and described therein this concept is unsatisfactory for developing composite action in panel construction because it is substantially lacking in the number of prongs or teeth necessary to resist the normal shearing stresses that would develop in a panel under average loading conditions, thus causing the panel to deflect excessively. In addition, this structure requires at least three separate elements to function--a web and either two opposed plates or one plate with a tension chord member, a detriment similarly found in the Falkenberg device.
Accordingly it is felt that most users of such devices would find it desirable to have a single piece structural fastener formed in various shapes which would require only one other element to function with that element being a penetrable plate such as a plywood sheet or the like. A single piece structural fastener with novel pointed teeth could then be used to reduce fabrication time and materials and could be easily attached to the penetrable plate at the job site for quick erection time.
The novel teeth configuration and tooth spacing used on a single piece structural fastener of the applicant's design would then permit a wide variety of structural shapes to be constructed which would be suitable to overcome the many stress applications in various building structures.